//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regalloc"
-#include "PhysRegTracker.h"
+#include "LiveDebugVariables.h"
+#include "LiveRangeEdit.h"
#include "VirtRegMap.h"
+#include "VirtRegRewriter.h"
+#include "Spiller.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Function.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/ADT/EquivalenceClasses.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <set>
#include <queue>
#include <memory>
#include <cmath>
+
using namespace llvm;
STATISTIC(NumIters , "Number of iterations performed");
STATISTIC(NumBacktracks, "Number of times we had to backtrack");
STATISTIC(NumCoalesce, "Number of copies coalesced");
+STATISTIC(NumDowngrade, "Number of registers downgraded");
static cl::opt<bool>
NewHeuristic("new-spilling-heuristic",
cl::desc("Use new spilling heuristic"),
cl::init(false), cl::Hidden);
+static cl::opt<bool>
+PreSplitIntervals("pre-alloc-split",
+ cl::desc("Pre-register allocation live interval splitting"),
+ cl::init(false), cl::Hidden);
+
+static cl::opt<bool>
+TrivCoalesceEnds("trivial-coalesce-ends",
+ cl::desc("Attempt trivial coalescing of interval ends"),
+ cl::init(false), cl::Hidden);
+
static RegisterRegAlloc
-linearscanRegAlloc("linearscan", " linear scan register allocator",
+linearscanRegAlloc("linearscan", "linear scan register allocator",
createLinearScanRegisterAllocator);
namespace {
- struct VISIBILITY_HIDDEN RALinScan : public MachineFunctionPass {
+ // When we allocate a register, add it to a fixed-size queue of
+ // registers to skip in subsequent allocations. This trades a small
+ // amount of register pressure and increased spills for flexibility in
+ // the post-pass scheduler.
+ //
+ // Note that in a the number of registers used for reloading spills
+ // will be one greater than the value of this option.
+ //
+ // One big limitation of this is that it doesn't differentiate between
+ // different register classes. So on x86-64, if there is xmm register
+ // pressure, it can caused fewer GPRs to be held in the queue.
+ static cl::opt<unsigned>
+ NumRecentlyUsedRegs("linearscan-skip-count",
+ cl::desc("Number of registers for linearscan to remember"
+ "to skip."),
+ cl::init(0),
+ cl::Hidden);
+
+ struct RALinScan : public MachineFunctionPass {
static char ID;
- RALinScan() : MachineFunctionPass(&ID) {}
+ RALinScan() : MachineFunctionPass(ID) {
+ initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
+ initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
+ initializeStrongPHIEliminationPass(*PassRegistry::getPassRegistry());
+ initializeRegisterCoalescerAnalysisGroup(
+ *PassRegistry::getPassRegistry());
+ initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
+ initializePreAllocSplittingPass(*PassRegistry::getPassRegistry());
+ initializeLiveStacksPass(*PassRegistry::getPassRegistry());
+ initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
+ initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
+ initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
+ initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
+
+ // Initialize the queue to record recently-used registers.
+ if (NumRecentlyUsedRegs > 0)
+ RecentRegs.resize(NumRecentlyUsedRegs, 0);
+ RecentNext = RecentRegs.begin();
+ }
typedef std::pair<LiveInterval*, LiveInterval::iterator> IntervalPtr;
typedef SmallVector<IntervalPtr, 32> IntervalPtrs;
EquivalenceClasses<const TargetRegisterClass*> RelatedRegClasses;
DenseMap<unsigned, const TargetRegisterClass*> OneClassForEachPhysReg;
+ // NextReloadMap - For each register in the map, it maps to the another
+ // register which is defined by a reload from the same stack slot and
+ // both reloads are in the same basic block.
+ DenseMap<unsigned, unsigned> NextReloadMap;
+
+ // DowngradedRegs - A set of registers which are being "downgraded", i.e.
+ // un-favored for allocation.
+ SmallSet<unsigned, 8> DowngradedRegs;
+
+ // DowngradeMap - A map from virtual registers to physical registers being
+ // downgraded for the virtual registers.
+ DenseMap<unsigned, unsigned> DowngradeMap;
+
MachineFunction* mf_;
MachineRegisterInfo* mri_;
const TargetMachine* tm_;
const TargetRegisterInfo* tri_;
const TargetInstrInfo* tii_;
BitVector allocatableRegs_;
+ BitVector reservedRegs_;
LiveIntervals* li_;
- LiveStacks* ls_;
- const MachineLoopInfo *loopInfo;
+ MachineLoopInfo *loopInfo;
/// handled_ - Intervals are added to the handled_ set in the order of their
/// start value. This is uses for backtracking.
SmallVector<LiveInterval*, 64>,
greater_ptr<LiveInterval> > IntervalHeap;
IntervalHeap unhandled_;
- std::auto_ptr<PhysRegTracker> prt_;
- std::auto_ptr<VirtRegMap> vrm_;
+
+ /// regUse_ - Tracks register usage.
+ SmallVector<unsigned, 32> regUse_;
+ SmallVector<unsigned, 32> regUseBackUp_;
+
+ /// vrm_ - Tracks register assignments.
+ VirtRegMap* vrm_;
+
+ std::auto_ptr<VirtRegRewriter> rewriter_;
+
std::auto_ptr<Spiller> spiller_;
+ // The queue of recently-used registers.
+ SmallVector<unsigned, 4> RecentRegs;
+ SmallVector<unsigned, 4>::iterator RecentNext;
+
+ // Record that we just picked this register.
+ void recordRecentlyUsed(unsigned reg) {
+ assert(reg != 0 && "Recently used register is NOREG!");
+ if (!RecentRegs.empty()) {
+ *RecentNext++ = reg;
+ if (RecentNext == RecentRegs.end())
+ RecentNext = RecentRegs.begin();
+ }
+ }
+
public:
virtual const char* getPassName() const {
return "Linear Scan Register Allocator";
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addRequired<AliasAnalysis>();
+ AU.addPreserved<AliasAnalysis>();
AU.addRequired<LiveIntervals>();
+ AU.addPreserved<SlotIndexes>();
+ if (StrongPHIElim)
+ AU.addRequiredID(StrongPHIEliminationID);
// Make sure PassManager knows which analyses to make available
// to coalescing and which analyses coalescing invalidates.
AU.addRequiredTransitive<RegisterCoalescer>();
- AU.addRequired<LiveStacks>();
- AU.addPreserved<LiveStacks>();
+ AU.addRequired<CalculateSpillWeights>();
+ if (PreSplitIntervals)
+ AU.addRequiredID(PreAllocSplittingID);
+ AU.addRequiredID(LiveStacksID);
+ AU.addPreservedID(LiveStacksID);
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
+ AU.addRequired<VirtRegMap>();
+ AU.addPreserved<VirtRegMap>();
+ AU.addRequired<LiveDebugVariables>();
+ AU.addPreserved<LiveDebugVariables>();
+ AU.addRequiredID(MachineDominatorsID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
/// runOnMachineFunction - register allocate the whole function
bool runOnMachineFunction(MachineFunction&);
+ // Determine if we skip this register due to its being recently used.
+ bool isRecentlyUsed(unsigned reg) const {
+ return std::find(RecentRegs.begin(), RecentRegs.end(), reg) !=
+ RecentRegs.end();
+ }
+
private:
/// linearScan - the linear scan algorithm
void linearScan();
/// processActiveIntervals - expire old intervals and move non-overlapping
/// ones to the inactive list.
- void processActiveIntervals(unsigned CurPoint);
+ void processActiveIntervals(SlotIndex CurPoint);
/// processInactiveIntervals - expire old intervals and move overlapping
/// ones to the active list.
- void processInactiveIntervals(unsigned CurPoint);
+ void processInactiveIntervals(SlotIndex CurPoint);
+
+ /// hasNextReloadInterval - Return the next liveinterval that's being
+ /// defined by a reload from the same SS as the specified one.
+ LiveInterval *hasNextReloadInterval(LiveInterval *cur);
+
+ /// DowngradeRegister - Downgrade a register for allocation.
+ void DowngradeRegister(LiveInterval *li, unsigned Reg);
+
+ /// UpgradeRegister - Upgrade a register for allocation.
+ void UpgradeRegister(unsigned Reg);
/// assignRegOrStackSlotAtInterval - assign a register if one
/// is available, or spill.
void assignRegOrStackSlotAtInterval(LiveInterval* cur);
+ void updateSpillWeights(std::vector<float> &Weights,
+ unsigned reg, float weight,
+ const TargetRegisterClass *RC);
+
/// findIntervalsToSpill - Determine the intervals to spill for the
/// specified interval. It's passed the physical registers whose spill
/// weight is the lowest among all the registers whose live intervals
SmallVector<LiveInterval*, 8> &SpillIntervals);
/// attemptTrivialCoalescing - If a simple interval is defined by a copy,
- /// try allocate the definition the same register as the source register
- /// if the register is not defined during live time of the interval. This
- /// eliminate a copy. This is used to coalesce copies which were not
+ /// try to allocate the definition to the same register as the source,
+ /// if the register is not defined during the life time of the interval.
+ /// This eliminates a copy, and is used to coalesce copies which were not
/// coalesced away before allocation either due to dest and src being in
/// different register classes or because the coalescer was overly
/// conservative.
unsigned attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg);
///
- /// register handling helpers
+ /// Register usage / availability tracking helpers.
+ ///
+
+ void initRegUses() {
+ regUse_.resize(tri_->getNumRegs(), 0);
+ regUseBackUp_.resize(tri_->getNumRegs(), 0);
+ }
+
+ void finalizeRegUses() {
+#ifndef NDEBUG
+ // Verify all the registers are "freed".
+ bool Error = false;
+ for (unsigned i = 0, e = tri_->getNumRegs(); i != e; ++i) {
+ if (regUse_[i] != 0) {
+ dbgs() << tri_->getName(i) << " is still in use!\n";
+ Error = true;
+ }
+ }
+ if (Error)
+ llvm_unreachable(0);
+#endif
+ regUse_.clear();
+ regUseBackUp_.clear();
+ }
+
+ void addRegUse(unsigned physReg) {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ ++regUse_[physReg];
+ for (const unsigned* as = tri_->getAliasSet(physReg); *as; ++as)
+ ++regUse_[*as];
+ }
+
+ void delRegUse(unsigned physReg) {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ assert(regUse_[physReg] != 0);
+ --regUse_[physReg];
+ for (const unsigned* as = tri_->getAliasSet(physReg); *as; ++as) {
+ assert(regUse_[*as] != 0);
+ --regUse_[*as];
+ }
+ }
+
+ bool isRegAvail(unsigned physReg) const {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ return regUse_[physReg] == 0;
+ }
+
+ void backUpRegUses() {
+ regUseBackUp_ = regUse_;
+ }
+
+ void restoreRegUses() {
+ regUse_ = regUseBackUp_;
+ }
+
+ ///
+ /// Register handling helpers.
///
/// getFreePhysReg - return a free physical register for this virtual
/// register interval if we have one, otherwise return 0.
unsigned getFreePhysReg(LiveInterval* cur);
-
- /// assignVirt2StackSlot - assigns this virtual register to a
- /// stack slot. returns the stack slot
- int assignVirt2StackSlot(unsigned virtReg);
+ unsigned getFreePhysReg(LiveInterval* cur,
+ const TargetRegisterClass *RC,
+ unsigned MaxInactiveCount,
+ SmallVector<unsigned, 256> &inactiveCounts,
+ bool SkipDGRegs);
+
+ /// getFirstNonReservedPhysReg - return the first non-reserved physical
+ /// register in the register class.
+ unsigned getFirstNonReservedPhysReg(const TargetRegisterClass *RC) {
+ TargetRegisterClass::iterator aoe = RC->allocation_order_end(*mf_);
+ TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_);
+ while (i != aoe && reservedRegs_.test(*i))
+ ++i;
+ assert(i != aoe && "All registers reserved?!");
+ return *i;
+ }
void ComputeRelatedRegClasses();
template <typename ItTy>
void printIntervals(const char* const str, ItTy i, ItTy e) const {
- if (str) DOUT << str << " intervals:\n";
- for (; i != e; ++i) {
- DOUT << "\t" << *i->first << " -> ";
- unsigned reg = i->first->reg;
- if (TargetRegisterInfo::isVirtualRegister(reg)) {
- reg = vrm_->getPhys(reg);
- }
- DOUT << tri_->getName(reg) << '\n';
- }
+ DEBUG({
+ if (str)
+ dbgs() << str << " intervals:\n";
+
+ for (; i != e; ++i) {
+ dbgs() << '\t' << *i->first << " -> ";
+
+ unsigned reg = i->first->reg;
+ if (TargetRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+
+ dbgs() << tri_->getName(reg) << '\n';
+ }
+ });
}
};
char RALinScan::ID = 0;
}
-static RegisterPass<RALinScan>
-X("linearscan-regalloc", "Linear Scan Register Allocator");
+INITIALIZE_PASS_BEGIN(RALinScan, "linearscan-regalloc",
+ "Linear Scan Register Allocator", false, false)
+INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
+INITIALIZE_PASS_DEPENDENCY(StrongPHIElimination)
+INITIALIZE_PASS_DEPENDENCY(CalculateSpillWeights)
+INITIALIZE_PASS_DEPENDENCY(PreAllocSplitting)
+INITIALIZE_PASS_DEPENDENCY(LiveStacks)
+INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
+INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
+INITIALIZE_AG_DEPENDENCY(RegisterCoalescer)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_END(RALinScan, "linearscan-regalloc",
+ "Linear Scan Register Allocator", false, false)
void RALinScan::ComputeRelatedRegClasses() {
- const TargetRegisterInfo &TRI = *tri_;
-
// First pass, add all reg classes to the union, and determine at least one
// reg class that each register is in.
bool HasAliases = false;
- for (TargetRegisterInfo::regclass_iterator RCI = TRI.regclass_begin(),
- E = TRI.regclass_end(); RCI != E; ++RCI) {
+ for (TargetRegisterInfo::regclass_iterator RCI = tri_->regclass_begin(),
+ E = tri_->regclass_end(); RCI != E; ++RCI) {
RelatedRegClasses.insert(*RCI);
for (TargetRegisterClass::iterator I = (*RCI)->begin(), E = (*RCI)->end();
I != E; ++I) {
- HasAliases = HasAliases || *TRI.getAliasSet(*I) != 0;
-
+ HasAliases = HasAliases || *tri_->getAliasSet(*I) != 0;
+
const TargetRegisterClass *&PRC = OneClassForEachPhysReg[*I];
if (PRC) {
// Already processed this register. Just make sure we know that
}
}
}
-
+
// Second pass, now that we know conservatively what register classes each reg
// belongs to, add info about aliases. We don't need to do this for targets
// without register aliases.
for (DenseMap<unsigned, const TargetRegisterClass*>::iterator
I = OneClassForEachPhysReg.begin(), E = OneClassForEachPhysReg.end();
I != E; ++I)
- for (const unsigned *AS = TRI.getAliasSet(I->first); *AS; ++AS)
- RelatedRegClasses.unionSets(I->second, OneClassForEachPhysReg[*AS]);
+ for (const unsigned *AS = tri_->getAliasSet(I->first); *AS; ++AS) {
+ const TargetRegisterClass *AliasClass =
+ OneClassForEachPhysReg.lookup(*AS);
+ if (AliasClass)
+ RelatedRegClasses.unionSets(I->second, AliasClass);
+ }
}
-/// attemptTrivialCoalescing - If a simple interval is defined by a copy,
-/// try allocate the definition the same register as the source register
-/// if the register is not defined during live time of the interval. This
-/// eliminate a copy. This is used to coalesce copies which were not
-/// coalesced away before allocation either due to dest and src being in
-/// different register classes or because the coalescer was overly
-/// conservative.
+/// attemptTrivialCoalescing - If a simple interval is defined by a copy, try
+/// allocate the definition the same register as the source register if the
+/// register is not defined during live time of the interval. If the interval is
+/// killed by a copy, try to use the destination register. This eliminates a
+/// copy. This is used to coalesce copies which were not coalesced away before
+/// allocation either due to dest and src being in different register classes or
+/// because the coalescer was overly conservative.
unsigned RALinScan::attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg) {
- if ((cur.preference && cur.preference == Reg) || !cur.containsOneValue())
+ unsigned Preference = vrm_->getRegAllocPref(cur.reg);
+ if ((Preference && Preference == Reg) || !cur.containsOneValue())
return Reg;
- VNInfo *vni = cur.getValNumInfo(0);
- if (!vni->def || vni->def == ~1U || vni->def == ~0U)
+ // We cannot handle complicated live ranges. Simple linear stuff only.
+ if (cur.ranges.size() != 1)
return Reg;
- MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
- unsigned SrcReg, DstReg;
- if (!CopyMI || !tii_->isMoveInstr(*CopyMI, SrcReg, DstReg))
+
+ const LiveRange &range = cur.ranges.front();
+
+ VNInfo *vni = range.valno;
+ if (vni->isUnused() || !vni->def.isValid())
return Reg;
- if (TargetRegisterInfo::isVirtualRegister(SrcReg)) {
- if (!vrm_->isAssignedReg(SrcReg))
- return Reg;
+
+ unsigned CandReg;
+ {
+ MachineInstr *CopyMI;
+ if ((CopyMI = li_->getInstructionFromIndex(vni->def)) && CopyMI->isCopy())
+ // Defined by a copy, try to extend SrcReg forward
+ CandReg = CopyMI->getOperand(1).getReg();
+ else if (TrivCoalesceEnds &&
+ (CopyMI = li_->getInstructionFromIndex(range.end.getBaseIndex())) &&
+ CopyMI->isCopy() && cur.reg == CopyMI->getOperand(1).getReg())
+ // Only used by a copy, try to extend DstReg backwards
+ CandReg = CopyMI->getOperand(0).getReg();
else
- SrcReg = vrm_->getPhys(SrcReg);
+ return Reg;
+
+ // If the target of the copy is a sub-register then don't coalesce.
+ if(CopyMI->getOperand(0).getSubReg())
+ return Reg;
+ }
+
+ if (TargetRegisterInfo::isVirtualRegister(CandReg)) {
+ if (!vrm_->isAssignedReg(CandReg))
+ return Reg;
+ CandReg = vrm_->getPhys(CandReg);
}
- if (Reg == SrcReg)
+ if (Reg == CandReg)
return Reg;
const TargetRegisterClass *RC = mri_->getRegClass(cur.reg);
- if (!RC->contains(SrcReg))
+ if (!RC->contains(CandReg))
+ return Reg;
+
+ if (li_->conflictsWithPhysReg(cur, *vrm_, CandReg))
return Reg;
// Try to coalesce.
- if (!li_->conflictsWithPhysRegDef(cur, *vrm_, SrcReg)) {
- DOUT << "Coalescing: " << cur << " -> " << tri_->getName(SrcReg)
- << '\n';
- vrm_->clearVirt(cur.reg);
- vrm_->assignVirt2Phys(cur.reg, SrcReg);
- ++NumCoalesce;
- return SrcReg;
- }
+ DEBUG(dbgs() << "Coalescing: " << cur << " -> " << tri_->getName(CandReg)
+ << '\n');
+ vrm_->clearVirt(cur.reg);
+ vrm_->assignVirt2Phys(cur.reg, CandReg);
- return Reg;
+ ++NumCoalesce;
+ return CandReg;
}
bool RALinScan::runOnMachineFunction(MachineFunction &fn) {
tri_ = tm_->getRegisterInfo();
tii_ = tm_->getInstrInfo();
allocatableRegs_ = tri_->getAllocatableSet(fn);
+ reservedRegs_ = tri_->getReservedRegs(fn);
li_ = &getAnalysis<LiveIntervals>();
- ls_ = &getAnalysis<LiveStacks>();
loopInfo = &getAnalysis<MachineLoopInfo>();
// We don't run the coalescer here because we have no reason to
// If this is the first function compiled, compute the related reg classes.
if (RelatedRegClasses.empty())
ComputeRelatedRegClasses();
-
- if (!prt_.get()) prt_.reset(new PhysRegTracker(*tri_));
- vrm_.reset(new VirtRegMap(*mf_));
- if (!spiller_.get()) spiller_.reset(createSpiller());
+
+ // Also resize register usage trackers.
+ initRegUses();
+
+ vrm_ = &getAnalysis<VirtRegMap>();
+ if (!rewriter_.get()) rewriter_.reset(createVirtRegRewriter());
+
+ spiller_.reset(createSpiller(*this, *mf_, *vrm_));
initIntervalSets();
linearScan();
// Rewrite spill code and update the PhysRegsUsed set.
- spiller_->runOnMachineFunction(*mf_, *vrm_);
- vrm_.reset(); // Free the VirtRegMap
+ rewriter_->runOnMachineFunction(*mf_, *vrm_, li_);
+
+ // Write out new DBG_VALUE instructions.
+ getAnalysis<LiveDebugVariables>().emitDebugValues(vrm_);
assert(unhandled_.empty() && "Unhandled live intervals remain!");
+
+ finalizeRegUses();
+
fixed_.clear();
active_.clear();
inactive_.clear();
handled_.clear();
+ NextReloadMap.clear();
+ DowngradedRegs.clear();
+ DowngradeMap.clear();
+ spiller_.reset(0);
return true;
}
for (LiveIntervals::iterator i = li_->begin(), e = li_->end(); i != e; ++i) {
if (TargetRegisterInfo::isPhysicalRegister(i->second->reg)) {
- mri_->setPhysRegUsed(i->second->reg);
- fixed_.push_back(std::make_pair(i->second, i->second->begin()));
- } else
- unhandled_.push(i->second);
+ if (!i->second->empty()) {
+ mri_->setPhysRegUsed(i->second->reg);
+ fixed_.push_back(std::make_pair(i->second, i->second->begin()));
+ }
+ } else {
+ if (i->second->empty()) {
+ assignRegOrStackSlotAtInterval(i->second);
+ }
+ else
+ unhandled_.push(i->second);
+ }
}
}
-void RALinScan::linearScan()
-{
+void RALinScan::linearScan() {
// linear scan algorithm
- DOUT << "********** LINEAR SCAN **********\n";
- DOUT << "********** Function: " << mf_->getFunction()->getName() << '\n';
-
- DEBUG(printIntervals("fixed", fixed_.begin(), fixed_.end()));
+ DEBUG({
+ dbgs() << "********** LINEAR SCAN **********\n"
+ << "********** Function: "
+ << mf_->getFunction()->getName() << '\n';
+ printIntervals("fixed", fixed_.begin(), fixed_.end());
+ });
while (!unhandled_.empty()) {
// pick the interval with the earliest start point
LiveInterval* cur = unhandled_.top();
unhandled_.pop();
++NumIters;
- DOUT << "\n*** CURRENT ***: " << *cur << '\n';
+ DEBUG(dbgs() << "\n*** CURRENT ***: " << *cur << '\n');
- if (!cur->empty()) {
- processActiveIntervals(cur->beginNumber());
- processInactiveIntervals(cur->beginNumber());
+ assert(!cur->empty() && "Empty interval in unhandled set.");
- assert(TargetRegisterInfo::isVirtualRegister(cur->reg) &&
- "Can only allocate virtual registers!");
- }
+ processActiveIntervals(cur->beginIndex());
+ processInactiveIntervals(cur->beginIndex());
+
+ assert(TargetRegisterInfo::isVirtualRegister(cur->reg) &&
+ "Can only allocate virtual registers!");
// Allocating a virtual register. try to find a free
// physical register or spill an interval (possibly this one) in order to
// assign it one.
assignRegOrStackSlotAtInterval(cur);
- DEBUG(printIntervals("active", active_.begin(), active_.end()));
- DEBUG(printIntervals("inactive", inactive_.begin(), inactive_.end()));
+ DEBUG({
+ printIntervals("active", active_.begin(), active_.end());
+ printIntervals("inactive", inactive_.begin(), inactive_.end());
+ });
}
- // expire any remaining active intervals
+ // Expire any remaining active intervals
while (!active_.empty()) {
IntervalPtr &IP = active_.back();
unsigned reg = IP.first->reg;
- DOUT << "\tinterval " << *IP.first << " expired\n";
+ DEBUG(dbgs() << "\tinterval " << *IP.first << " expired\n");
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
+ delRegUse(reg);
active_.pop_back();
}
- // expire any remaining inactive intervals
- DEBUG(for (IntervalPtrs::reverse_iterator
- i = inactive_.rbegin(); i != inactive_.rend(); ++i)
- DOUT << "\tinterval " << *i->first << " expired\n");
+ // Expire any remaining inactive intervals
+ DEBUG({
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend(); ++i)
+ dbgs() << "\tinterval " << *i->first << " expired\n";
+ });
inactive_.clear();
// Add live-ins to every BB except for entry. Also perform trivial coalescing.
// Ignore splited live intervals.
if (!isPhys && vrm_->getPreSplitReg(cur.reg))
continue;
+
for (LiveInterval::Ranges::const_iterator I = cur.begin(), E = cur.end();
I != E; ++I) {
const LiveRange &LR = *I;
- if (li_->findLiveInMBBs(LR, LiveInMBBs)) {
+ if (li_->findLiveInMBBs(LR.start, LR.end, LiveInMBBs)) {
for (unsigned i = 0, e = LiveInMBBs.size(); i != e; ++i)
- if (LiveInMBBs[i] != EntryMBB)
+ if (LiveInMBBs[i] != EntryMBB) {
+ assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
+ "Adding a virtual register to livein set?");
LiveInMBBs[i]->addLiveIn(Reg);
+ }
LiveInMBBs.clear();
}
}
}
- DOUT << *vrm_;
+ DEBUG(dbgs() << *vrm_);
+
+ // Look for physical registers that end up not being allocated even though
+ // register allocator had to spill other registers in its register class.
+ if (!vrm_->FindUnusedRegisters(li_))
+ return;
}
/// processActiveIntervals - expire old intervals and move non-overlapping ones
/// to the inactive list.
-void RALinScan::processActiveIntervals(unsigned CurPoint)
+void RALinScan::processActiveIntervals(SlotIndex CurPoint)
{
- DOUT << "\tprocessing active intervals:\n";
+ DEBUG(dbgs() << "\tprocessing active intervals:\n");
for (unsigned i = 0, e = active_.size(); i != e; ++i) {
LiveInterval *Interval = active_[i].first;
IntervalPos = Interval->advanceTo(IntervalPos, CurPoint);
if (IntervalPos == Interval->end()) { // Remove expired intervals.
- DOUT << "\t\tinterval " << *Interval << " expired\n";
+ DEBUG(dbgs() << "\t\tinterval " << *Interval << " expired\n");
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
+ delRegUse(reg);
// Pop off the end of the list.
active_[i] = active_.back();
} else if (IntervalPos->start > CurPoint) {
// Move inactive intervals to inactive list.
- DOUT << "\t\tinterval " << *Interval << " inactive\n";
+ DEBUG(dbgs() << "\t\tinterval " << *Interval << " inactive\n");
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
+ delRegUse(reg);
// add to inactive.
inactive_.push_back(std::make_pair(Interval, IntervalPos));
/// processInactiveIntervals - expire old intervals and move overlapping
/// ones to the active list.
-void RALinScan::processInactiveIntervals(unsigned CurPoint)
+void RALinScan::processInactiveIntervals(SlotIndex CurPoint)
{
- DOUT << "\tprocessing inactive intervals:\n";
+ DEBUG(dbgs() << "\tprocessing inactive intervals:\n");
for (unsigned i = 0, e = inactive_.size(); i != e; ++i) {
LiveInterval *Interval = inactive_[i].first;
IntervalPos = Interval->advanceTo(IntervalPos, CurPoint);
if (IntervalPos == Interval->end()) { // remove expired intervals.
- DOUT << "\t\tinterval " << *Interval << " expired\n";
+ DEBUG(dbgs() << "\t\tinterval " << *Interval << " expired\n");
// Pop off the end of the list.
inactive_[i] = inactive_.back();
--i; --e;
} else if (IntervalPos->start <= CurPoint) {
// move re-activated intervals in active list
- DOUT << "\t\tinterval " << *Interval << " active\n";
+ DEBUG(dbgs() << "\t\tinterval " << *Interval << " active\n");
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->addRegUse(reg);
+ addRegUse(reg);
// add to active
active_.push_back(std::make_pair(Interval, IntervalPos));
/// updateSpillWeights - updates the spill weights of the specifed physical
/// register and its weight.
-static void updateSpillWeights(std::vector<float> &Weights,
- unsigned reg, float weight,
- const TargetRegisterInfo *TRI) {
+void RALinScan::updateSpillWeights(std::vector<float> &Weights,
+ unsigned reg, float weight,
+ const TargetRegisterClass *RC) {
+ SmallSet<unsigned, 4> Processed;
+ SmallSet<unsigned, 4> SuperAdded;
+ SmallVector<unsigned, 4> Supers;
Weights[reg] += weight;
- for (const unsigned* as = TRI->getAliasSet(reg); *as; ++as)
+ Processed.insert(reg);
+ for (const unsigned* as = tri_->getAliasSet(reg); *as; ++as) {
Weights[*as] += weight;
+ Processed.insert(*as);
+ if (tri_->isSubRegister(*as, reg) &&
+ SuperAdded.insert(*as) &&
+ RC->contains(*as)) {
+ Supers.push_back(*as);
+ }
+ }
+
+ // If the alias is a super-register, and the super-register is in the
+ // register class we are trying to allocate. Then add the weight to all
+ // sub-registers of the super-register even if they are not aliases.
+ // e.g. allocating for GR32, bh is not used, updating bl spill weight.
+ // bl should get the same spill weight otherwise it will be choosen
+ // as a spill candidate since spilling bh doesn't make ebx available.
+ for (unsigned i = 0, e = Supers.size(); i != e; ++i) {
+ for (const unsigned *sr = tri_->getSubRegisters(Supers[i]); *sr; ++sr)
+ if (!Processed.count(*sr))
+ Weights[*sr] += weight;
+ }
}
static
return IP.end();
}
-static void RevertVectorIteratorsTo(RALinScan::IntervalPtrs &V, unsigned Point){
+static void RevertVectorIteratorsTo(RALinScan::IntervalPtrs &V,
+ SlotIndex Point){
for (unsigned i = 0, e = V.size(); i != e; ++i) {
RALinScan::IntervalPtr &IP = V[i];
LiveInterval::iterator I = std::upper_bound(IP.first->begin(),
}
}
-/// addStackInterval - Create a LiveInterval for stack if the specified live
-/// interval has been spilled.
-static void addStackInterval(LiveInterval *cur, LiveStacks *ls_,
- LiveIntervals *li_, float &Weight,
- VirtRegMap &vrm_) {
- int SS = vrm_.getStackSlot(cur->reg);
- if (SS == VirtRegMap::NO_STACK_SLOT)
- return;
- LiveInterval &SI = ls_->getOrCreateInterval(SS);
- SI.weight += Weight;
-
- VNInfo *VNI;
- if (SI.getNumValNums())
- VNI = SI.getValNumInfo(0);
- else
- VNI = SI.getNextValue(~0U, 0, ls_->getVNInfoAllocator());
-
- LiveInterval &RI = li_->getInterval(cur->reg);
- // FIXME: This may be overly conservative.
- SI.MergeRangesInAsValue(RI, VNI);
-}
-
/// getConflictWeight - Return the number of conflicts between cur
/// live interval and defs and uses of Reg weighted by loop depthes.
-static float getConflictWeight(LiveInterval *cur, unsigned Reg,
- LiveIntervals *li_,
- MachineRegisterInfo *mri_,
- const MachineLoopInfo *loopInfo) {
+static
+float getConflictWeight(LiveInterval *cur, unsigned Reg, LiveIntervals *li_,
+ MachineRegisterInfo *mri_,
+ MachineLoopInfo *loopInfo) {
float Conflicts = 0;
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(Reg),
E = mri_->reg_end(); I != E; ++I) {
MachineInstr *MI = &*I;
if (cur->liveAt(li_->getInstructionIndex(MI))) {
unsigned loopDepth = loopInfo->getLoopDepth(MI->getParent());
- Conflicts += powf(10.0f, (float)loopDepth);
+ Conflicts += std::pow(10.0f, (float)loopDepth);
}
}
return Conflicts;
float Conflicts[3] = { 0.0f, 0.0f, 0.0f };
SmallVector<LiveInterval*, 8> SLIs[3];
- DOUT << "\tConsidering " << NumCands << " candidates: ";
- DEBUG(for (unsigned i = 0; i != NumCands; ++i)
- DOUT << tri_->getName(Candidates[i].first) << " ";
- DOUT << "\n";);
-
+ DEBUG({
+ dbgs() << "\tConsidering " << NumCands << " candidates: ";
+ for (unsigned i = 0; i != NumCands; ++i)
+ dbgs() << tri_->getName(Candidates[i].first) << " ";
+ dbgs() << "\n";
+ });
+
// Calculate the number of conflicts of each candidate.
for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
unsigned Reg = i->first->reg;
namespace {
struct WeightCompare {
+ private:
+ const RALinScan &Allocator;
+
+ public:
+ WeightCompare(const RALinScan &Alloc) : Allocator(Alloc) {}
+
typedef std::pair<unsigned, float> RegWeightPair;
bool operator()(const RegWeightPair &LHS, const RegWeightPair &RHS) const {
- return LHS.second < RHS.second;
+ return LHS.second < RHS.second && !Allocator.isRecentlyUsed(LHS.first);
}
};
}
return (diff / w2) <= 0.05f; // Within 5%.
}
+LiveInterval *RALinScan::hasNextReloadInterval(LiveInterval *cur) {
+ DenseMap<unsigned, unsigned>::iterator I = NextReloadMap.find(cur->reg);
+ if (I == NextReloadMap.end())
+ return 0;
+ return &li_->getInterval(I->second);
+}
+
+void RALinScan::DowngradeRegister(LiveInterval *li, unsigned Reg) {
+ for (const unsigned *AS = tri_->getOverlaps(Reg); *AS; ++AS) {
+ bool isNew = DowngradedRegs.insert(*AS);
+ (void)isNew; // Silence compiler warning.
+ assert(isNew && "Multiple reloads holding the same register?");
+ DowngradeMap.insert(std::make_pair(li->reg, *AS));
+ }
+ ++NumDowngrade;
+}
+
+void RALinScan::UpgradeRegister(unsigned Reg) {
+ if (Reg) {
+ DowngradedRegs.erase(Reg);
+ for (const unsigned *AS = tri_->getAliasSet(Reg); *AS; ++AS)
+ DowngradedRegs.erase(*AS);
+ }
+}
+
+namespace {
+ struct LISorter {
+ bool operator()(LiveInterval* A, LiveInterval* B) {
+ return A->beginIndex() < B->beginIndex();
+ }
+ };
+}
+
/// assignRegOrStackSlotAtInterval - assign a register if one is available, or
/// spill.
-void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur)
-{
- DOUT << "\tallocating current interval: ";
+void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur) {
+ const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
+ DEBUG(dbgs() << "\tallocating current interval from "
+ << RC->getName() << ": ");
// This is an implicitly defined live interval, just assign any register.
- const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
if (cur->empty()) {
- unsigned physReg = cur->preference;
+ unsigned physReg = vrm_->getRegAllocPref(cur->reg);
if (!physReg)
- physReg = *RC->allocation_order_begin(*mf_);
- DOUT << tri_->getName(physReg) << '\n';
+ physReg = getFirstNonReservedPhysReg(RC);
+ DEBUG(dbgs() << tri_->getName(physReg) << '\n');
// Note the register is not really in use.
vrm_->assignVirt2Phys(cur->reg, physReg);
return;
}
- PhysRegTracker backupPrt = *prt_;
+ backUpRegUses();
std::vector<std::pair<unsigned, float> > SpillWeightsToAdd;
- unsigned StartPosition = cur->beginNumber();
+ SlotIndex StartPosition = cur->beginIndex();
const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
- // If this live interval is defined by a move instruction and its source is
- // assigned a physical register that is compatible with the target register
- // class, then we should try to assign it the same register.
+ // If start of this live interval is defined by a move instruction and its
+ // source is assigned a physical register that is compatible with the target
+ // register class, then we should try to assign it the same register.
// This can happen when the move is from a larger register class to a smaller
// one, e.g. X86::mov32to32_. These move instructions are not coalescable.
- if (!cur->preference && cur->containsOneValue()) {
- VNInfo *vni = cur->getValNumInfo(0);
- if (vni->def && vni->def != ~1U && vni->def != ~0U) {
+ if (!vrm_->getRegAllocPref(cur->reg) && cur->hasAtLeastOneValue()) {
+ VNInfo *vni = cur->begin()->valno;
+ if (!vni->isUnused() && vni->def.isValid()) {
MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
- unsigned SrcReg, DstReg;
- if (CopyMI && tii_->isMoveInstr(*CopyMI, SrcReg, DstReg)) {
+ if (CopyMI && CopyMI->isCopy()) {
+ unsigned DstSubReg = CopyMI->getOperand(0).getSubReg();
+ unsigned SrcReg = CopyMI->getOperand(1).getReg();
+ unsigned SrcSubReg = CopyMI->getOperand(1).getSubReg();
unsigned Reg = 0;
if (TargetRegisterInfo::isPhysicalRegister(SrcReg))
Reg = SrcReg;
else if (vrm_->isAssignedReg(SrcReg))
Reg = vrm_->getPhys(SrcReg);
- if (Reg && allocatableRegs_[Reg] && RC->contains(Reg))
- cur->preference = Reg;
+ if (Reg) {
+ if (SrcSubReg)
+ Reg = tri_->getSubReg(Reg, SrcSubReg);
+ if (DstSubReg)
+ Reg = tri_->getMatchingSuperReg(Reg, DstSubReg, RC);
+ if (Reg && allocatableRegs_[Reg] && RC->contains(Reg))
+ mri_->setRegAllocationHint(cur->reg, 0, Reg);
+ }
}
}
}
- // for every interval in inactive we overlap with, mark the
+ // For every interval in inactive we overlap with, mark the
// register as not free and update spill weights.
for (IntervalPtrs::const_iterator i = inactive_.begin(),
e = inactive_.end(); i != e; ++i) {
assert(TargetRegisterInfo::isVirtualRegister(Reg) &&
"Can only allocate virtual registers!");
const TargetRegisterClass *RegRC = mri_->getRegClass(Reg);
- // If this is not in a related reg class to the register we're allocating,
+ // If this is not in a related reg class to the register we're allocating,
// don't check it.
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
cur->overlapsFrom(*i->first, i->second-1)) {
Reg = vrm_->getPhys(Reg);
- prt_->addRegUse(Reg);
+ addRegUse(Reg);
SpillWeightsToAdd.push_back(std::make_pair(Reg, i->first->weight));
}
}
-
+
// Speculatively check to see if we can get a register right now. If not,
// we know we won't be able to by adding more constraints. If so, we can
// check to see if it is valid. Doing an exhaustive search of the fixed_ list
SmallSet<unsigned, 8> RegAliases;
for (const unsigned *AS = tri_->getAliasSet(physReg); *AS; ++AS)
RegAliases.insert(*AS);
-
+
bool ConflictsWithFixed = false;
for (unsigned i = 0, e = fixed_.size(); i != e; ++i) {
IntervalPtr &IP = fixed_[i];
// Okay, this reg is on the fixed list. Check to see if we actually
// conflict.
LiveInterval *I = IP.first;
- if (I->endNumber() > StartPosition) {
+ if (I->endIndex() > StartPosition) {
LiveInterval::iterator II = I->advanceTo(IP.second, StartPosition);
IP.second = II;
if (II != I->begin() && II->start > StartPosition)
}
}
}
-
+
// Okay, the register picked by our speculative getFreePhysReg call turned
// out to be in use. Actually add all of the conflicting fixed registers to
- // prt so we can do an accurate query.
+ // regUse_ so we can do an accurate query.
if (ConflictsWithFixed) {
// For every interval in fixed we overlap with, mark the register as not
// free and update spill weights.
LiveInterval *I = IP.first;
const TargetRegisterClass *RegRC = OneClassForEachPhysReg[I->reg];
- if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
- I->endNumber() > StartPosition) {
+ if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
+ I->endIndex() > StartPosition) {
LiveInterval::iterator II = I->advanceTo(IP.second, StartPosition);
IP.second = II;
if (II != I->begin() && II->start > StartPosition)
--II;
if (cur->overlapsFrom(*I, II)) {
unsigned reg = I->reg;
- prt_->addRegUse(reg);
+ addRegUse(reg);
SpillWeightsToAdd.push_back(std::make_pair(reg, I->weight));
}
}
}
- // Using the newly updated prt_ object, which includes conflicts in the
+ // Using the newly updated regUse_ object, which includes conflicts in the
// future, see if there are any registers available.
physReg = getFreePhysReg(cur);
}
}
-
+
// Restore the physical register tracker, removing information about the
// future.
- *prt_ = backupPrt;
-
- // if we find a free register, we are done: assign this virtual to
+ restoreRegUses();
+
+ // If we find a free register, we are done: assign this virtual to
// the free physical register and add this interval to the active
// list.
if (physReg) {
- DOUT << tri_->getName(physReg) << '\n';
+ DEBUG(dbgs() << tri_->getName(physReg) << '\n');
+ assert(RC->contains(physReg) && "Invalid candidate");
vrm_->assignVirt2Phys(cur->reg, physReg);
- prt_->addRegUse(physReg);
+ addRegUse(physReg);
active_.push_back(std::make_pair(cur, cur->begin()));
handled_.push_back(cur);
+
+ // "Upgrade" the physical register since it has been allocated.
+ UpgradeRegister(physReg);
+ if (LiveInterval *NextReloadLI = hasNextReloadInterval(cur)) {
+ // "Downgrade" physReg to try to keep physReg from being allocated until
+ // the next reload from the same SS is allocated.
+ mri_->setRegAllocationHint(NextReloadLI->reg, 0, physReg);
+ DowngradeRegister(cur, physReg);
+ }
return;
}
- DOUT << "no free registers\n";
+ DEBUG(dbgs() << "no free registers\n");
// Compile the spill weights into an array that is better for scanning.
std::vector<float> SpillWeights(tri_->getNumRegs(), 0.0f);
for (std::vector<std::pair<unsigned, float> >::iterator
I = SpillWeightsToAdd.begin(), E = SpillWeightsToAdd.end(); I != E; ++I)
- updateSpillWeights(SpillWeights, I->first, I->second, tri_);
-
+ updateSpillWeights(SpillWeights, I->first, I->second, RC);
+
// for each interval in active, update spill weights.
for (IntervalPtrs::const_iterator i = active_.begin(), e = active_.end();
i != e; ++i) {
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- updateSpillWeights(SpillWeights, reg, i->first->weight, tri_);
+ updateSpillWeights(SpillWeights, reg, i->first->weight, RC);
}
-
- DOUT << "\tassigning stack slot at interval "<< *cur << ":\n";
+
+ DEBUG(dbgs() << "\tassigning stack slot at interval "<< *cur << ":\n");
// Find a register to spill.
float minWeight = HUGE_VALF;
- unsigned minReg = 0; /*cur->preference*/; // Try the preferred register first.
+ unsigned minReg = 0;
bool Found = false;
std::vector<std::pair<unsigned,float> > RegsWeights;
e = RC->allocation_order_end(*mf_); i != e; ++i) {
unsigned reg = *i;
float regWeight = SpillWeights[reg];
- if (minWeight > regWeight)
+ // Don't even consider reserved regs.
+ if (reservedRegs_.test(reg))
+ continue;
+ // Skip recently allocated registers and reserved registers.
+ if (minWeight > regWeight && !isRecentlyUsed(reg))
Found = true;
RegsWeights.push_back(std::make_pair(reg, regWeight));
}
-
+
// If we didn't find a register that is spillable, try aliases?
if (!Found) {
for (TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_),
e = RC->allocation_order_end(*mf_); i != e; ++i) {
unsigned reg = *i;
+ if (reservedRegs_.test(reg))
+ continue;
// No need to worry about if the alias register size < regsize of RC.
// We are going to spill all registers that alias it anyway.
for (const unsigned* as = tri_->getAliasSet(reg); *as; ++as)
}
// Sort all potential spill candidates by weight.
- std::sort(RegsWeights.begin(), RegsWeights.end(), WeightCompare());
+ std::sort(RegsWeights.begin(), RegsWeights.end(), WeightCompare(*this));
minReg = RegsWeights[0].first;
minWeight = RegsWeights[0].second;
if (minWeight == HUGE_VALF) {
// All registers must have inf weight. Just grab one!
- minReg = BestPhysReg ? BestPhysReg : *RC->allocation_order_begin(*mf_);
+ minReg = BestPhysReg ? BestPhysReg : getFirstNonReservedPhysReg(RC);
if (cur->weight == HUGE_VALF ||
li_->getApproximateInstructionCount(*cur) == 0) {
// Spill a physical register around defs and uses.
- li_->spillPhysRegAroundRegDefsUses(*cur, minReg, *vrm_);
- assignRegOrStackSlotAtInterval(cur);
+ if (li_->spillPhysRegAroundRegDefsUses(*cur, minReg, *vrm_)) {
+ // spillPhysRegAroundRegDefsUses may have invalidated iterator stored
+ // in fixed_. Reset them.
+ for (unsigned i = 0, e = fixed_.size(); i != e; ++i) {
+ IntervalPtr &IP = fixed_[i];
+ LiveInterval *I = IP.first;
+ if (I->reg == minReg || tri_->isSubRegister(minReg, I->reg))
+ IP.second = I->advanceTo(I->begin(), StartPosition);
+ }
+
+ DowngradedRegs.clear();
+ assignRegOrStackSlotAtInterval(cur);
+ } else {
+ assert(false && "Ran out of registers during register allocation!");
+ report_fatal_error("Ran out of registers during register allocation!");
+ }
return;
}
}
--LastCandidate;
}
- DOUT << "\t\tregister(s) with min weight(s): ";
- DEBUG(for (unsigned i = 0; i != LastCandidate; ++i)
- DOUT << tri_->getName(RegsWeights[i].first)
- << " (" << RegsWeights[i].second << ")\n");
+ DEBUG({
+ dbgs() << "\t\tregister(s) with min weight(s): ";
+
+ for (unsigned i = 0; i != LastCandidate; ++i)
+ dbgs() << tri_->getName(RegsWeights[i].first)
+ << " (" << RegsWeights[i].second << ")\n";
+ });
- // if the current has the minimum weight, we need to spill it and
+ // If the current has the minimum weight, we need to spill it and
// add any added intervals back to unhandled, and restart
// linearscan.
if (cur->weight != HUGE_VALF && cur->weight <= minWeight) {
- DOUT << "\t\t\tspilling(c): " << *cur << '\n';
- float SSWeight;
- SmallVector<LiveInterval*, 8> spillIs;
- std::vector<LiveInterval*> added =
- li_->addIntervalsForSpills(*cur, spillIs, loopInfo, *vrm_, SSWeight);
- addStackInterval(cur, ls_, li_, SSWeight, *vrm_);
+ DEBUG(dbgs() << "\t\t\tspilling(c): " << *cur << '\n');
+ SmallVector<LiveInterval*, 8> added;
+ LiveRangeEdit LRE(*cur, added);
+ spiller_->spill(LRE);
+
+ std::sort(added.begin(), added.end(), LISorter());
if (added.empty())
return; // Early exit if all spills were folded.
- // Merge added with unhandled. Note that we know that
- // addIntervalsForSpills returns intervals sorted by their starting
+ // Merge added with unhandled. Note that we have already sorted
+ // intervals returned by addIntervalsForSpills by their starting
// point.
- for (unsigned i = 0, e = added.size(); i != e; ++i)
- unhandled_.push(added[i]);
+ // This also update the NextReloadMap. That is, it adds mapping from a
+ // register defined by a reload from SS to the next reload from SS in the
+ // same basic block.
+ MachineBasicBlock *LastReloadMBB = 0;
+ LiveInterval *LastReload = 0;
+ int LastReloadSS = VirtRegMap::NO_STACK_SLOT;
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ LiveInterval *ReloadLi = added[i];
+ if (ReloadLi->weight == HUGE_VALF &&
+ li_->getApproximateInstructionCount(*ReloadLi) == 0) {
+ SlotIndex ReloadIdx = ReloadLi->beginIndex();
+ MachineBasicBlock *ReloadMBB = li_->getMBBFromIndex(ReloadIdx);
+ int ReloadSS = vrm_->getStackSlot(ReloadLi->reg);
+ if (LastReloadMBB == ReloadMBB && LastReloadSS == ReloadSS) {
+ // Last reload of same SS is in the same MBB. We want to try to
+ // allocate both reloads the same register and make sure the reg
+ // isn't clobbered in between if at all possible.
+ assert(LastReload->beginIndex() < ReloadIdx);
+ NextReloadMap.insert(std::make_pair(LastReload->reg, ReloadLi->reg));
+ }
+ LastReloadMBB = ReloadMBB;
+ LastReload = ReloadLi;
+ LastReloadSS = ReloadSS;
+ }
+ unhandled_.push(ReloadLi);
+ }
return;
}
++NumBacktracks;
- // push the current interval back to unhandled since we are going
+ // Push the current interval back to unhandled since we are going
// to re-run at least this iteration. Since we didn't modify it it
// should go back right in the front of the list
unhandled_.push(cur);
// The earliest start of a Spilled interval indicates up to where
// in handled we need to roll back
- unsigned earliestStart = cur->beginNumber();
+ assert(!spillIs.empty() && "No spill intervals?");
+ SlotIndex earliestStart = spillIs[0]->beginIndex();
// Spill live intervals of virtual regs mapped to the physical register we
// want to clear (and its aliases). We only spill those that overlap with the
// current interval as the rest do not affect its allocation. we also keep
// track of the earliest start of all spilled live intervals since this will
// mark our rollback point.
- std::vector<LiveInterval*> added;
+ SmallVector<LiveInterval*, 8> added;
while (!spillIs.empty()) {
LiveInterval *sli = spillIs.back();
spillIs.pop_back();
- DOUT << "\t\t\tspilling(a): " << *sli << '\n';
- earliestStart = std::min(earliestStart, sli->beginNumber());
- float SSWeight;
- std::vector<LiveInterval*> newIs =
- li_->addIntervalsForSpills(*sli, spillIs, loopInfo, *vrm_, SSWeight);
- addStackInterval(sli, ls_, li_, SSWeight, *vrm_);
- std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ DEBUG(dbgs() << "\t\t\tspilling(a): " << *sli << '\n');
+ if (sli->beginIndex() < earliestStart)
+ earliestStart = sli->beginIndex();
+ LiveRangeEdit LRE(*sli, added, 0, &spillIs);
+ spiller_->spill(LRE);
spilled.insert(sli->reg);
}
- DOUT << "\t\trolling back to: " << earliestStart << '\n';
+ // Include any added intervals in earliestStart.
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ SlotIndex SI = added[i]->beginIndex();
+ if (SI < earliestStart)
+ earliestStart = SI;
+ }
+
+ DEBUG(dbgs() << "\t\trolling back to: " << earliestStart << '\n');
// Scan handled in reverse order up to the earliest start of a
// spilled live interval and undo each one, restoring the state of
while (!handled_.empty()) {
LiveInterval* i = handled_.back();
// If this interval starts before t we are done.
- if (i->beginNumber() < earliestStart)
+ if (!i->empty() && i->beginIndex() < earliestStart)
break;
- DOUT << "\t\t\tundo changes for: " << *i << '\n';
+ DEBUG(dbgs() << "\t\t\tundo changes for: " << *i << '\n');
handled_.pop_back();
// When undoing a live interval allocation we must know if it is active or
- // inactive to properly update the PhysRegTracker and the VirtRegMap.
+ // inactive to properly update regUse_ and the VirtRegMap.
IntervalPtrs::iterator it;
if ((it = FindIntervalInVector(active_, i)) != active_.end()) {
active_.erase(it);
assert(!TargetRegisterInfo::isPhysicalRegister(i->reg));
if (!spilled.count(i->reg))
unhandled_.push(i);
- prt_->delRegUse(vrm_->getPhys(i->reg));
+ delRegUse(vrm_->getPhys(i->reg));
vrm_->clearVirt(i->reg);
} else if ((it = FindIntervalInVector(inactive_, i)) != inactive_.end()) {
inactive_.erase(it);
unhandled_.push(i);
}
- // It interval has a preference, it must be defined by a copy. Clear the
- // preference now since the source interval allocation may have been undone
- // as well.
- i->preference = 0;
+ DenseMap<unsigned, unsigned>::iterator ii = DowngradeMap.find(i->reg);
+ if (ii == DowngradeMap.end())
+ // It interval has a preference, it must be defined by a copy. Clear the
+ // preference now since the source interval allocation may have been
+ // undone as well.
+ mri_->setRegAllocationHint(i->reg, 0, 0);
+ else {
+ UpgradeRegister(ii->second);
+ }
}
// Rewind the iterators in the active, inactive, and fixed lists back to the
RevertVectorIteratorsTo(inactive_, earliestStart);
RevertVectorIteratorsTo(fixed_, earliestStart);
- // scan the rest and undo each interval that expired after t and
+ // Scan the rest and undo each interval that expired after t and
// insert it in active (the next iteration of the algorithm will
// put it in inactive if required)
for (unsigned i = 0, e = handled_.size(); i != e; ++i) {
LiveInterval *HI = handled_[i];
if (!HI->expiredAt(earliestStart) &&
- HI->expiredAt(cur->beginNumber())) {
- DOUT << "\t\t\tundo changes for: " << *HI << '\n';
+ HI->expiredAt(cur->beginIndex())) {
+ DEBUG(dbgs() << "\t\t\tundo changes for: " << *HI << '\n');
active_.push_back(std::make_pair(HI, HI->begin()));
assert(!TargetRegisterInfo::isPhysicalRegister(HI->reg));
- prt_->addRegUse(vrm_->getPhys(HI->reg));
+ addRegUse(vrm_->getPhys(HI->reg));
}
}
- // merge added with unhandled
- for (unsigned i = 0, e = added.size(); i != e; ++i)
- unhandled_.push(added[i]);
+ // Merge added with unhandled.
+ // This also update the NextReloadMap. That is, it adds mapping from a
+ // register defined by a reload from SS to the next reload from SS in the
+ // same basic block.
+ MachineBasicBlock *LastReloadMBB = 0;
+ LiveInterval *LastReload = 0;
+ int LastReloadSS = VirtRegMap::NO_STACK_SLOT;
+ std::sort(added.begin(), added.end(), LISorter());
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ LiveInterval *ReloadLi = added[i];
+ if (ReloadLi->weight == HUGE_VALF &&
+ li_->getApproximateInstructionCount(*ReloadLi) == 0) {
+ SlotIndex ReloadIdx = ReloadLi->beginIndex();
+ MachineBasicBlock *ReloadMBB = li_->getMBBFromIndex(ReloadIdx);
+ int ReloadSS = vrm_->getStackSlot(ReloadLi->reg);
+ if (LastReloadMBB == ReloadMBB && LastReloadSS == ReloadSS) {
+ // Last reload of same SS is in the same MBB. We want to try to
+ // allocate both reloads the same register and make sure the reg
+ // isn't clobbered in between if at all possible.
+ assert(LastReload->beginIndex() < ReloadIdx);
+ NextReloadMap.insert(std::make_pair(LastReload->reg, ReloadLi->reg));
+ }
+ LastReloadMBB = ReloadMBB;
+ LastReload = ReloadLi;
+ LastReloadSS = ReloadSS;
+ }
+ unhandled_.push(ReloadLi);
+ }
+}
+
+unsigned RALinScan::getFreePhysReg(LiveInterval* cur,
+ const TargetRegisterClass *RC,
+ unsigned MaxInactiveCount,
+ SmallVector<unsigned, 256> &inactiveCounts,
+ bool SkipDGRegs) {
+ unsigned FreeReg = 0;
+ unsigned FreeRegInactiveCount = 0;
+
+ std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(cur->reg);
+ // Resolve second part of the hint (if possible) given the current allocation.
+ unsigned physReg = Hint.second;
+ if (TargetRegisterInfo::isVirtualRegister(physReg) && vrm_->hasPhys(physReg))
+ physReg = vrm_->getPhys(physReg);
+
+ TargetRegisterClass::iterator I, E;
+ tie(I, E) = tri_->getAllocationOrder(RC, Hint.first, physReg, *mf_);
+ assert(I != E && "No allocatable register in this register class!");
+
+ // Scan for the first available register.
+ for (; I != E; ++I) {
+ unsigned Reg = *I;
+ // Ignore "downgraded" registers.
+ if (SkipDGRegs && DowngradedRegs.count(Reg))
+ continue;
+ // Skip reserved registers.
+ if (reservedRegs_.test(Reg))
+ continue;
+ // Skip recently allocated registers.
+ if (isRegAvail(Reg) && !isRecentlyUsed(Reg)) {
+ FreeReg = Reg;
+ if (FreeReg < inactiveCounts.size())
+ FreeRegInactiveCount = inactiveCounts[FreeReg];
+ else
+ FreeRegInactiveCount = 0;
+ break;
+ }
+ }
+
+ // If there are no free regs, or if this reg has the max inactive count,
+ // return this register.
+ if (FreeReg == 0 || FreeRegInactiveCount == MaxInactiveCount) {
+ // Remember what register we picked so we can skip it next time.
+ if (FreeReg != 0) recordRecentlyUsed(FreeReg);
+ return FreeReg;
+ }
+
+ // Continue scanning the registers, looking for the one with the highest
+ // inactive count. Alkis found that this reduced register pressure very
+ // slightly on X86 (in rev 1.94 of this file), though this should probably be
+ // reevaluated now.
+ for (; I != E; ++I) {
+ unsigned Reg = *I;
+ // Ignore "downgraded" registers.
+ if (SkipDGRegs && DowngradedRegs.count(Reg))
+ continue;
+ // Skip reserved registers.
+ if (reservedRegs_.test(Reg))
+ continue;
+ if (isRegAvail(Reg) && Reg < inactiveCounts.size() &&
+ FreeRegInactiveCount < inactiveCounts[Reg] && !isRecentlyUsed(Reg)) {
+ FreeReg = Reg;
+ FreeRegInactiveCount = inactiveCounts[Reg];
+ if (FreeRegInactiveCount == MaxInactiveCount)
+ break; // We found the one with the max inactive count.
+ }
+ }
+
+ // Remember what register we picked so we can skip it next time.
+ recordRecentlyUsed(FreeReg);
+
+ return FreeReg;
}
/// getFreePhysReg - return a free physical register for this virtual register
unsigned RALinScan::getFreePhysReg(LiveInterval *cur) {
SmallVector<unsigned, 256> inactiveCounts;
unsigned MaxInactiveCount = 0;
-
+
const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
-
+
for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
i != e; ++i) {
unsigned reg = i->first->reg;
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
- // If this is not in a related reg class to the register we're allocating,
+ // If this is not in a related reg class to the register we're allocating,
// don't check it.
const TargetRegisterClass *RegRC = mri_->getRegClass(reg);
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader) {
}
}
- unsigned FreeReg = 0;
- unsigned FreeRegInactiveCount = 0;
-
// If copy coalescer has assigned a "preferred" register, check if it's
// available first.
- if (cur->preference) {
- if (prt_->isRegAvail(cur->preference) &&
- RC->contains(cur->preference)) {
- DOUT << "\t\tassigned the preferred register: "
- << tri_->getName(cur->preference) << "\n";
- return cur->preference;
- } else
- DOUT << "\t\tunable to assign the preferred register: "
- << tri_->getName(cur->preference) << "\n";
+ unsigned Preference = vrm_->getRegAllocPref(cur->reg);
+ if (Preference) {
+ DEBUG(dbgs() << "(preferred: " << tri_->getName(Preference) << ") ");
+ if (isRegAvail(Preference) &&
+ RC->contains(Preference))
+ return Preference;
}
- // Scan for the first available register.
- TargetRegisterClass::iterator I = RC->allocation_order_begin(*mf_);
- TargetRegisterClass::iterator E = RC->allocation_order_end(*mf_);
- assert(I != E && "No allocatable register in this register class!");
- for (; I != E; ++I)
- if (prt_->isRegAvail(*I)) {
- FreeReg = *I;
- if (FreeReg < inactiveCounts.size())
- FreeRegInactiveCount = inactiveCounts[FreeReg];
- else
- FreeRegInactiveCount = 0;
- break;
- }
-
- // If there are no free regs, or if this reg has the max inactive count,
- // return this register.
- if (FreeReg == 0 || FreeRegInactiveCount == MaxInactiveCount) return FreeReg;
-
- // Continue scanning the registers, looking for the one with the highest
- // inactive count. Alkis found that this reduced register pressure very
- // slightly on X86 (in rev 1.94 of this file), though this should probably be
- // reevaluated now.
- for (; I != E; ++I) {
- unsigned Reg = *I;
- if (prt_->isRegAvail(Reg) && Reg < inactiveCounts.size() &&
- FreeRegInactiveCount < inactiveCounts[Reg]) {
- FreeReg = Reg;
- FreeRegInactiveCount = inactiveCounts[Reg];
- if (FreeRegInactiveCount == MaxInactiveCount)
- break; // We found the one with the max inactive count.
- }
+ if (!DowngradedRegs.empty()) {
+ unsigned FreeReg = getFreePhysReg(cur, RC, MaxInactiveCount, inactiveCounts,
+ true);
+ if (FreeReg)
+ return FreeReg;
}
-
- return FreeReg;
+ return getFreePhysReg(cur, RC, MaxInactiveCount, inactiveCounts, false);
}
FunctionPass* llvm::createLinearScanRegisterAllocator() {
projects / oota-llvm.git / blobdiff